Quantitative assessment of immediate cutaneous hypersensitivity in a mouse model exhibiting an IgE response to Timothy grass allergens.

BACKGROUND

A variety of allergic reactions can be induced in mice, as measured by the induction of specific IgE. Functional read-out parameters include skin reactions and airway constriction. The aim of this study was to establish an improved quantitative assessment of the immediate cutaneous hypersensitivity reaction in a mouse model.

MATERIAL/METHODS: Timothy grass pollen was used to sensitize BALB/c mice, which were monitored for hypersensitivity reactions by Western blot analysis of the IgE response, determination of specific immunoglobulin subclasses by ELISA, and a skin test. The immediate cutaneous hypersensitivity reaction (ICHR) was assessed by pretreating the animals with an intravenous injection of Evans blue before anesthesia and provoking a reaction by intradermal application of the allergen. Ensuing blue coloring at the injection site could be seen as an indication of mast cell degranulation and the areas of 'wheal and flare' reaction were documented for digital imaging and quantitative analysis.

RESULTS

Analysis using an antigen-specific ELISA showed that sensitization with pollen extract induced the production of specific IgE, IgG1, IgG2a and IgG2b antibodies. Western blot analyses demonstrated the production of specific IgE antibodies analogous to the IgE reactivity pattern found in allergic patients. The production of IgE was concurrent with a positive ICHR to these allergens. Quantitative analysis demonstrated that the area of ICHR increased in size in correlation to the dose of allergen applied.

CONCLUSIONS

This model and the mode of skin reactivity analysis may serve as a tool to evaluate new hyposensitization and therapeutic strategies for pollen allergy.